Shaping the Response: The Role of FcRI and Syk Expression Levels in Mast Cell Signalling

A. Nag, J. R. Faeder, B. Goldstein

Research output: Contribution to journalArticlepeer-review

12 Scopus Citations


Many receptor systems initiate cell signalling through ligand-induced receptor aggregation. For bivalent ligands binding to mono- or bivalent receptors a plot of the equilibrium concentration of receptors in aggregates against the log of the free ligand concentration the cross-linking curve is symmetric and bell shaped. However steady state cellular responses initiated through receptor cross-linking may have a different dependence on ligand concentration than the aggregated receptors that initiate and maintain these responses. The authors illustrate by considering the activation of the protein kinase Syk that rapidly occurs after high affinity receptors for IgE FcεRI are aggregated on the surface of mast cells and basophils. Using a mathematical model of Syk activation the authors investigate two effects one straightforward and one less so that result in Syk activation not qualitatively following the cross-linking curve. Model predictions show that if the mechanism by which Syk is fully activated involves the transphosphorylation of Syk by Syk then Syk activation curves can be either bell shaped or double humped depending on the cellular concentrations of Syk and FcεRI. The model also predicts that the Syk activation curve can be non-symmetric with respect to the ligand concentration. The cell can exhibit differential Syk activation at two different ligand concentrations that produce identical distributions of receptor aggregates that form and dissociate at the same rates. The authors discuss how even though it is only receptor aggregates that trigger responses differences in total ligand concentration can lead to subtle kinetic effects that yield qualitative differences in the levels of Syk activation.

Original languageAmerican English
Pages (from-to)334-347
Number of pages14
JournalIET Systems Biology
Issue number6
StatePublished - Nov 2010

NREL Publication Number

  • NREL/JA-2C00-50241


  • cellular information processing


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